In considering how machines can range in their intellectual ability, it is useful to consider varying levels of human intelligence. While all humans possess the ability to think and act independently, their ability to do so in a useful way varies considerably. At low levels of intelligence, humans can carry out repetitive tasks that they are taught how to do, and with rising intelligence comes the ability to learn more quickly and to reason independently. While machines and humans differ qualitatively in the way they find solutions to problems, the varying intelligences of humans does provide a useful analogy for understanding the variance in artificial intelligence.